International Application PCT/US2003/035348 entitled “Implanted Outer Ear Canal Hearing Aid” (incorporated herein by reference) describes a system including a sound generating implant configured for implantation in the soft tissue between a patient's ear canal and his retro-auricular space. The implant preferably comprises a case having a proximal end subcutaneously implanted proximate to the patient's retro-auricular space and a distal end implanted proximate to the patient's outer ear canal. An electric/acoustic transducer, e.g., a speaker is mounted at the case distal end for producing sound energy which is projected into the patient's outer ear canal. The case distal end can terminate just under the skin surrounding the ear canal or can percutaneously protrude into the canal. The hearing aid system also includes an acoustic/electric transducer, e.g., a microphone, located remote from the implant, e.g., in an external housing carried by the patient. The microphone produces an electric signal representative of audible sound which can be coupled by wireless telemetry to drive the implant speaker.
International Application PCT/US2004/011079 entitled “Percutaneously Implantable Medical Device Configured To Promote Tissue Ingrowth” (incorporated herein by reference) describes an exemplary implant structure configured for use in a hearing aid system of the type described in the aforementioned '035348 PCT application. The exemplary implant structure includes a case, or housing, having a body portion and a forwardly projecting stud at the case distal end adapted to project percutaneously into the patients outer ear canal. A porous material is preferably provided on the outer surface of the stud to promote healthy tissue ingrowth for anchoring the implant and forming a bacteria resistant barrier.